1. Field of the Invention
Embodiments of the invention generally relate to a load lock chamber for transferring large area substrates into a vacuum processing system and methods of operation of the same.
2. Description of the Related Art
Thin film transistors (TFT) are commonly used for active matrix displays such as computer and television monitors, cell phone displays, personal digital assistants (PDAs), and an increasing number of other devices. Generally, flat panels comprise two glass plates having a layer of liquid crystal materials sandwiched therebetween. At least one of the glass plates includes one conductive film disposed thereon that is coupled to a power source. Power, supplied to the conductive film from the power source, changes the orientation of the crystal material, creating a pattern display.
With the marketplace's acceptance of flat panel technology, the demand for larger displays, increased production and lower manufacturing costs have driven equipment manufacturers to develop new systems that accommodate larger size glass substrates for flat panel display fabricators. Current glass processing equipment is generally configured to accommodate substrates up to about one square meter. Processing equipment configured to accommodate substrate sizes up to and exceeding 1½ square meters is envisioned in the immediate future.
Equipment to fabricate such large substrates represents a substantial investment to flat panel display fabricators. Conventional systems require large and expensive hardware. In order to offset this investment, high substrate throughput is highly desirable.
FIG. 9 is a simplified schematic of a double dual slot load lock chamber 900 available from AKT™, a wholly owned division of Applied Materials Inc., located in Santa Clara, Calif., that is currently capable of transferring 1500×1800 mm substrates at a rate of about 60 substrates per hour. The load lock chamber 900 includes two substrate transfer chambers 902, 904 formed in a chamber body 906. Each substrate transfer chamber 902, 904 has an interior volume of about 800 liters. Two substrates 910 are disposed on an elevator 912 that is vertically movable within the chamber 902, 904 to facilitate exchange of the substrates with transfer robots (not shown).
To achieve high substrate throughput, load lock chambers, such as the one described above, require high capacity vacuum pumps and venting systems. However, increasing the throughput of such high volume load lock chambers is challenging. Simply increasing the pumping and venting speeds does not provide an acceptable solution as high pumping speeds may contribute to particulate contamination of the substrate within the load lock chamber. Moreover, as cleanrooms generally operate at humidity levels greater than 50 percent to minimize static electricity, rapid venting of the load lock chamber may undesirably result in condensation of water vapor within the load lock chamber. As future processing systems are envisioned to process even larger size substrates, the need for improved load lock chambers capable of rapid transfer of large area substrates is of increasing concern.
Thus, there is a need for an improved load lock chamber for large area substrates.